What Muffler?

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ENGINR

Wannabe Racer
Joined
Nov 6, 2005
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Location
Melbourne
I need to shut my car up ALOT. I'm running a 3" dump into a 3" stainless exhaust through a highflow 3" cat and resonator into a 4" titanium X-Force muffler. It looks the goods and sounds great but I must be getting old because it's just too damn loud for me now and I want to quieten it up - but not compromise flow.

At the moment I've got a 2.25" section flanged on with a jasma muffler to shut it up and it's great, but I think this reduction in size is the restriction that's the big holdup to my flowing more boost. What mufflers would you guys recommend that won't inhibit flow but will keep the exhaust noise legal?
 
I have a 3" muffler with an oval body that has twin outlets on it. It's still a straight through muffler, it's gotta flow pretty well considering the power my nugget makes, and it's pretty quiet - far better than standard straight through cannons (which I hate with a passion). The exhaust also has a single 4" resonator about 2 feet back from the muffler. It wouldn't be legal, but it would come close.

If you squint, you can kind of see it in this photo .. but it's a bit dark.

Maybe try and find a muffler with that sort of design?

edit: You could also give one of those Varex mufflers a try .. then you can vary the noise level around. I'm not convinced on their reliability though.
 
I was in the same boat,

i wanted a quiet car, but also with performance as well.

i ended up buying this, its a XForce Varex Muffler.





it has a butterfly valve inside which when closed makes the exhaust goes traverse the outside of the cannon a few times, basically making the car quieter than stock!

here is the sales video of the Varex, basically sold me :)

http://youtube.com/watch?v=K7jGYnhbQQU

cant wait to hook it up.

im going to use an output on my ECU to control it, so when ever i am above 25% throttle it will open automagically :D
 
X-Force Varex FTW!!! I got one for my brother and I and it quietens his exhaust up brilliantly! it works just like the video and the best decision we both made for a muffler ever. Good for late nights without pissing off the neighbours :wink: Simply press the button and hold it to fully close the butterfly and its quiet as! Rev the engine and it sounds like a stock non turbo car. Press the button again and hold it til it fullly opens and you get the loud Mitsu throaty sound :twisted:

Here's some more pics:

PICS: http://www.evocoupe.net/forum/viewtopic.php?t=3324&postdays=0&postorder=asc&highlight=varex&start=15

FITTED: http://orion2001.gallery.netspace.net.au/albums/Engine/Zorst001.jpg

p71_02.jpg
 
A friend of mine had a similar device in his GTR, except it bolted into a flange rather than being built into the muffler like a varex. Anyway, the car was supposed to be making power .. but struggled to make 280rwkw. Pulled the butterfly out, and bam .. 415kw atw. As it turned out, the flow through the exhaust was forcing the butterfly in the exhaust which drastically limited power.

edit: How far down the body is the butterfly too? Will you still be able to get a typical af meter up it?
 
steve said:
A friend of mine had a similar device in his GTR, except it bolted into a flange rather than being built into the muffler like a varex.
Click to expand...

yup, thats the APEXI one, they restrict the power big time, because there isnt anywhere for the exhaust gas to flow. its just basically a butterfly in a 3" pipe. when closed thats it, the flow is stopped.

the Varex still has passages for the exhaust, but obviously will not make as much power when closed as it would when open.
 
yup, thats the APEXI one, they restrict the power big time, because there isnt anywhere for the exhaust gas to flow. its just basically a butterfly in a 3" pipe. when closed thats it, the flow is stopped.
Click to expand...
No .. you're missing it. This was when the butterfly was set to open (so effectively the configuration of the exhaust is exactly the same as the Varex in full open mode). The problem was, the flow of the exhaust was enough to force the butterfly to close (even though the device itself was set to full open) .. not completely, but enough to take nearly 30% of the car's power.
 
magnaflow are the biz, iv'e got a 3'' cat and oval muffler on mine,
sounds good and no loss of power from when i replaced my old
fujitsubo ones, or if you want something legal could ring hitech mufflers who do some good stuff.
Grant.
 
steve said:
No .. you're missing it. This was when the butterfly was set to open (so effectively the configuration of the exhaust is exactly the same as the Varex in full open mode). The problem was, the flow of the exhaust was enough to force the butterfly to close (even though the device itself was set to full open) .. not completely, but enough to take nearly 30% of the car's power.
Click to expand...

no i wasnt missing it, you didnt explain that till then ;)

but i bet there was a lot more to it than what you just said,

A). for instance, if the valve is placed is a section of the exhaust that is straight, then it only has parallel flow to deal with.

B). but if the valve is placed on a bend, then its working with perpendicular flow, which under large flow instances could/would force the valve closed.

you also have the issue of the valve dividing the exhaust pluse, but thats another story.

i suspect that most of the power loss was due to incorrect installation, because even taking into account the cross sectional area of the open valve and the exhaust pulse disturbance there would be no way it would add up to the kw you mentioned. ;)

if the valve was not facing completely parallel to the exhaust, forcing it to close, then B). would be the case, causing the power loss you guys observed.
 
Hmmm.. Lots of options.

Thanks guys, I'll take a look at the Varex mufflers though, I spoke to their Vic distributor and they'll have some more in stock shortly.
 
The valve was about half way along the exhaust, on a straight section. The car had no cat, so nothing to disturb the flow. The wastegate also vented to the atmosphere (hence it was difficult to tell the exhaust note was getting quieter as the screamer was open), so wasn't adding any further disturbance.

Exhaust flow isn't straight either - the exhaust turbine adds a lot of turbulence, as do any bends in the exhaust. Exhaust gas has velocity and mass, and hence momentum, so it won't magically straighten itself out as soon as it hits a straight section. Whilst these 'waves' will lessen as distance increases (so having the butterfly at the back of the car as with the varex will be better), they don't get cancelled out entirely.

It was neither A or B .. more likely the device itself (you were right, it was the Apexi one) was poorly designed, and with age, lost tension in the actuator that held it open, allowing the exhaust flow to disturb it's orientation.

Maybe the varex is better, so good luck with yours .. even without the above, I'd avoid it due to it's cannon design :lol:
 
From seeing it and hearing it in action on my brother's car I have been more than impressed with it and how much it quietens the car. You obviously cant get up it when the butterfly is closed, but the whole point of having it closed is to quieten it up when you need to. Trust me, once you have it installed in your car you wont be disappointed, even if the cross section of the butterfly does rob a little power, it's well worth having so you dont attract bad attention :D
 
I've been thinking about this for a while now- having an actuated exhaust controlled by the ECU. It would help build boost too having lots of backpressure.
 
The Apexi butterfly valve I've seen is operated manually through a cable that's connected to a lever in the cabin. I've looked at this and wouldn't go near it with a 10 foot pole when there's electrically operated valves/options out there.
 
I put a 2.5" in twin 3 out magnaflow, it made a pretty big difference. In the US theres a muffler called "spintech", it apparently works really well silencing exhausts, but only under exhaust pressure. Probably a combination of a spintech with resonators and a muffler to keep the idle quiet would be pretty good.
 

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